The present invention relates to a turbomachinery such as a pump and a compressor, and more particularly to a centrifugal turbomachinery flowing out a fluid in a centrifugal direction from an impeller.
An example of a conventional centrifugal turbomachinery is disclosed in JP-A-11-324987. In the centrifugal turbomachinery disclosed in this publication, in order to downsize without lowering a fluid performance, on inlet end portion of return blades is located in an inner side in a radial direction than a position in a radial direction of a semi-open portion passage. Further, a circular pipe shaped space continuously provided with the semi-open portion passage is formed in an outer side in the radial direction than the return blade inlet side end portion. Accordingly, a stream flowing out from the semi-open portion passage can flow in without being regulated by a plurality of return blades arranged in a peripheral direction so as to form a circular blade row, and a loss at a time of flowing into the return blade is lowered.